I have to say it's actually a better Windows 7 you can choose, so to speak or switch back and forth which desktop you want to have either the usual like "Windows 7" or with lots of tiles and apps.
Device Manager, libraries, settings, programs install, Control Panel, Windows Update is just to use as with Win7.
In addition, there are just many more apps and nice gimmicks which did not exist in Win7.
The change from 7 to Win8.1 is not really worth talking about, I do not understand why you do it sometimes win so bad.
That's why I did it first installed on my old notebook which was actually nothing.
Manage many as startup has become easier directly in Task Manager.
And have to say solely on the appearance looks Win8.1 much better and more modern one notices right away.